1. Technical Field
The present invention relates to an ultrasonic transducer, an ultrasonic probe, and an ultrasonic examination device.
2. Background Technology
An ultrasonic transducer in which a plurality of ultrasonic elements are arranged in a matrix pattern has been known. This ultrasonic transducer includes a substrate that has a plurality of openings, a supporting film that is provided on the substrate so as to cover each of the openings, and a piezoelectric element that is provided on a part of the supporting film corresponding to each of the openings. A diaphragm is constructed by the part of the supporting film corresponding to the opening which is a part coinciding with the opening of the supporting film in a planar view. The ultrasonic element is constructed by the diaphragm and the piezoelectric element provided on the diaphragm. The thickness of the supporting film of the ultrasonic transducer, that is, the thickness of the part of the supporting film corresponding to the opening which coincides with the opening of the supporting film in a planar view is set to be uniform (for example, see Patent Document 1). In the ultrasonic transducer, the diaphragm is greatly deflected when ultrasonic waves are transmitted, and the diaphragm is slightly deflected when ultrasonic waves are received.
The well-known ultrasonic transducer, however, has a problem that the diaphragm is greatly deflected especially when ultrasonic waves are transmitted, which causes the stress to concentrate in the vicinity of an outer edge portion of the diaphragm and causes damage such as cracking or chipping. On the other hand, if the thickness of the diaphragm is increased to improve the strength of the diaphragm, the diaphragm will become hard to deflect. Then, especially when ultrasonic waves are received with the ultrasonic element, the deflection amount of the diaphragm will become smaller, which makes the stress generated in the piezoelectric element very small. Consequently, the level of a reception signal output from the piezoelectric element will be deteriorated. In other words, the characteristics of transmission and reception of ultrasonic waves, in particular, the sensitivity in reception will be deteriorated.
Japanese Laid-open Patent Publication No. 2000-23296 (Patent Document 1) is an example of the related art.